TheRock CycleChapters 5 & 6

What are the types of rock?

• Igneous rocks• Form from cooling magma• Recall: magma is molten material

beneath Earth’s surface• Sedimentary rocks

• Form from cementing and compacting pieces of sediment

• Sediment is pieces of solid material deposited on Earth’s surface

• Metamorphic rocks• Rocks that have been changed

from heat and pressure

Igneous Rocks

• Formation of igneous rock• Intrusive

• Formed by magma that cools slowly

• Formed beneath the Earth’s surface

• Coarse-grained• Ex. granite

• Extrusive• Formed by magma that cools

quickly• Formed above the Earth’s

surface• Fine-grained• Ex. Rhyolite

• Properties of igneous rock• Mineral composition

• Light colored = felsic• Dark colored = mafic

• Grain size• Coarse-grained = intrusive• Fine-grained = extrusive

Sedimentary Rocks

• Formation of sedimentary rock• Weathering produces sediments

• Physical weathering• Happens when rock

fragments break off.• Ex.

• Temperature changes expand or contract rock

• Living organisms like trees crack rocks

• Chemical weathering• Happens when the minerals

in rocks are chemically changed

• Ex.• Dissolving• Oxidation (rust)

• Erosion transports weathered sediments from one place to another

• Types of erosion• Wind• Moving water• Gravity• Glaciers

• Deposition is when sediments are laid down on the ground or under water

• This can cause sorting of sediments into layers, which is called bedding.

• Deposited sediments become buried

http://www.classzone.com/books/earth_science/terc/content/visualizations/es0604/es0604page01.cfm?chapter_no=visualization

• Lithification happens when the weight of overlaying sediments forces grains closer together.

• Water is pressed out• Sand is compacted• High temperatures (~3-4km

deep) cause cementation• New minerals can grow

between cemented sediments

• Properties of sedimentary rock

• Clastic—formed from deposits of loose sediments

http://www.classzone.com/books/earth_science/terc/content/visualizations/es0605/es0605page01.cfm?chapter_no=visualization• Chemical—formed from

precipitation of minerals dissolved in water

• Organic—formed from accumulation and lithification of dead organisms

• Ex. coal

Metamorphic Rocks

• Formation of metamorphic rocks

• High temperatures and pressures increase with depth

• High temperature comes from Earth’s internal heat or intruding magma.

• High pressure comes from overlying rock or the compression of mountain building

• Rocks do not melt, but change in texture, mineralogy, or chemical composition

http://www.classzone.com/books/earth_science/terc/content/visualizations/es0607/es0607page01.cfm?chapter_no=visualization

• Properties of metamorphic rocks

• Texture• Foliated—wavy layers and

bands of minerals• Nonfoliated—minerals form

blocky crystals• Mineral composition

• Heat & pressure can change one mineral into another

• Chemical composition• Hot fluids go in and out of

the rock during metamorphism, changing its chemistry

What is the rock cycle?

• The rock cycle is the continuous changing and remaking of rocks

• Any type of rock can turn into any other type of rock

• Matter making up rocks is neither crated nor destroyed, but simply changed.

• Processes that power the rock cycle

• Internal processes• Uplift• Heat & pressure• Melting• Cooling & crystallization

• External processes• Uplift• Weathering & erosion• Deposition, burial, & lithification